Puppet-Tale

Disclaimer- so if the title is bad if you all can help with the title please and thanks you. Also I don't own undertale that is Toby Fox.

Little Frisk was curious about Mt. Ebott. So they walked up and fell down. That is where they met so many different monsters.
They found out that they can save a and reset. So with that power, they done three different endings, Neutral, Pacifist, and Genocide. After knowing all the bad things that happen in Genocide, they reset.
Now they are in the pacifist run with a happy ending and with all of their friends.
As the days go by, Frisk and Sans start having nightmare of past timeline. Only Frisk knows them too well and to Sans, they seem familiar. The nightmares are the same, it is about THEM. THEY are planning to be a puppet master. Sans and Frisk has to deal with THEM, but first deal with their daily lives.

Warning this will have flashbacks in the start to set the story and the mood. Also spoilers to the game, to both of the main runs. Also sorry if the characters are not them lol, I will try my best.